Intangible Assets - Residential MSRs Activity (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Fair value of MSRs:
Beginning balance	$ 159us-gaap_ServicingAssetAtFairValueAmount	$ 227us-gaap_ServicingAssetAtFairValueAmount
Changes in fair value due to:
Changes in fair value due to changes in valuation model inputs or assumptions	(11)	(12)
Reductions related to customer payments	(8)	(10)
Ending balance	$ 140us-gaap_ServicingAssetAtFairValueAmount	$ 205us-gaap_ServicingAssetAtFairValueAmount

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Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

+ Details

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- Details

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- Definition

The net increase or decrease in fair value as a result of changes in the inputs used to calculate the fair value of servicing assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(4)(i)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

+ Details

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- Definition

The net Increase or Decrease in fair value as a result of other changes that are not additions, disposals, or a result of change in the inputs, assumptions, or model used to calculate the fair value of servicing assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 860

-SubTopic 50

-Section 50

-Paragraph 3

-Subparagraph (a)(4)(ii)

-URI http://asc.fasb.org/extlink&oid=7882072&loc=d3e122625-111746

+ Details

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